Machines for die casting various metals, such as aluminum, brass, zinc, magnesium, etc., have been known for many years. In one particular type of die casting machine, a gravity feed machine, molten metal is ladled into a shot sleeve through a pour hole. A plunger operating within the shot sleeve then forces the molten metal to flow through the sleeve into an affixed die.
One problem that has plagued die casting machines is that the molten metals tend to react chemically, thermally and/or metallurgically with the materials, usually steel or a steel alloy, that compose the shot sleeve wherever they come into contact. This reaction is especially prevalent when the molten metal exceeds a prescribed temperature at which such reaction occurs or is promoted. This reaction tends to corrode and to erode deformities into the surface of the shot sleeve hindering and eventually precluding effective operation of the die casting machine and, thus, requiring replacement of the shot sleeve. Especially troublesome damaging reactions have been found to occur when aluminum was the cast metal due its particularly high casting temperature (around 1200 degrees F. or greater).
Replacement of the shot sleeve is an expensive and time consuming task due in part to the size and cost of the sleeve and and its intimate engagement with the die.